Static Code Analysis with .editorconfig

Generally speaking, either an application or a system is built mostly by a team or a group of people. One of the first exercises building a dev team is to set up a standard development environment and configuration. It is because the whole team needs to have the same standard to avoid situations like "It works on my machine!". One of the activities of the typical development environment setup is "coding conventions". To achieve this, adding the .editorconfig file to the development source code is a good approach. Throughout this post, I'm going to discuss how we use the .editorconfig for C# static code analysis and coding style conventions.

.editorconfig

According to EditorConfig.org, they define themselves like:

EditorConfig helps maintain consistent coding styles for multiple developers working on the same project across various editors and IDEs. The EditorConfig project consists of a file format for defining coding styles and a collection of text editor plugins that enable editors to read the file format and adhere to defined styles. EditorConfig files are easily readable, and they work nicely with version control systems.

In other words, we define the .editorconfig file and simply put it into the root directory of the project. Then it provides indications of how consistently we keep our coding style. Of course, we can have the control that the project cannot be compiled if there are any coding style violations found. How can we apply the .editorconfig into our .NET project?

FxCop Analyzer

If you have been developing your applications through Visual Studio, you might have heard of code analysis tools like FxCop and StyleCop. Both seem to do similar jobs. The former performs analysis against the compiled binaries while the latter does against the source codes. However, since the Roslyn was introduced, instead of FxCop, the FxCop Analyzers is used. It doesn't even rely on Visual Studio, but can be downloaded as a NuGet package per project.

Using the FxCop Analyzers is really simple and easy. Run the following command to download the NuGet package into your project. Full stop. At the time of this writing, the latest version is 2.9.4.

Alternatively, you can directly modify the .csproj file to install the NuGet package.

Once the package is installed into your project and compile it, it analyses your code and shows underlines in red (error) and green (warning). Some of you may wonder where the analysis standards come. Microsoft publishes the .NET Framework Software Design Guidelines, which is the ground rule of the analysis. Therefore, based on these guidelines, FxCop Analyzers perform analysis of our codes. What if our project has slightly different standards? In this case, we can apply custom rule sets. There are pre-defined .ruleset files as templates in the NuGet package directory. Copy one of them from there and paste it into our project root.

Like the screenshot above, copy the AllRulesDefault.ruleset file into our root directory of the project, and update the .csproj file.

Now, our .csproj file has the reference to AllRulesDefault.ruleset. It looks like the following code snippet. If we change the Action attribute to None, Warning or Error, the FxCop Analyzers detects the changes and reflects it for analysis.

Unfortunately, this FxCop Analyzers can't replace .editorconfig, so this .ruleset file is recommended to use as a complement to it. The complete list of options for .editorconfig that supports FxCop Analyzers can be found at this page. As FxCop Analyzers keeps continuously being updated, this page is also updated regularly. I hope .editorconfig will replace FxCop Analyzers sooner rather than later.

.editorconfig as the Alternative of StyleCop

The more realistic approach using .editorconfig is to replace StyleCop. If it is located at the root directory, it automagically analyses the coding style. In addition to this, Visual Studio detects the file and overrides existing settings specific to the project. You can find the complete list of .editorconfig settings at this page.

One of the downsides of this .editorconfig is that there is no pre-defined set. Fortunately, Muhammad Rehan Saeed opens the pre-configured .editorconfig file, so you can use this as the starting point. Here are a part of the default settings. You can change the option value to either true or false and severity to silent for ignore, warning for warning, or error for compile error.

So far, we have discussed the way of static code analysis with .editorconfig. For coding conventions, it's mature enough to replace StyleCop. Although it's not there yet to replace FxCop Analyzers, it's just a matter of time. Therefore, in the meantime, the .ruleset file should be used to fill the gap.